Stabilized aircraft antenna



Nov. 13, 1951 N R. WARD 2,574,853

STABILIZED AIRCRAFT ANTENNA Filed Oct. 12, 1945 IN V EN TOR. ROGER WARD ATTORNEY scale on the instrument panel.

. continuously observe the variation in the abso- Paemed Nov. 13,1951

STABILIZED AIRCRAFT ANTENNA Roger Ward, Upper Falls, Md., assignor to The Glenn L. Martin Company, Middle River, Md.,

a corporation of Maryland Application October 12, 1945, Serial No. 622,005

Claims. (Cl. 244-77) This invention relates to a safety device, more particularly an automatic control for airplane flight controls to prevent the airplane from flying into obstructions. j One of the greatest hazards to an airplane in flight are weather conditions that prevent visible observation of the terrain to aid the pilot in so flying the airplane as to avoid sudden and unknown obstructions such as mountain ridges and peaks. While instrument flying has been de veloped to a high degree, there are still sufficient uncorrected variables that cause airplanes flyin with or without instruments to crash or fly into obstructions. By the development of the radio absolute altimeter, considerable guess work is taken out of altitude measurements. The altimeter consists of apparatus for sending ultra shortwave radiation downwardly from the aircraft and receiving the reflected wave from a point directly below the aircraft. By measuring the elapsed time of travel, an absolute measurement of the airplane above the ground directly below is obtained.

The principle of the absolute altimeter was applied in Patent 2,225,046 to P. B. Hunter, issued 'December 17, 1940, to effect a radio contour' The two waves separately measured altitude and the distance in front of the aircraft in a predetermined fixed angle. The distances so measured were transformed into visual indications on a The pilot could lute altitude and the variation of the distance along the forwardly directed beam andadjust the controls of the airplane in accordance with the observations of these scales. The difliculty of such a system arises from the fact that the system fails to take into consideration several factors. One, that the attitude of the airplane cannot be depended upon to remain so fixed while the plane is in flight that the indications on the scale will give true and dependable indications of the two measurements of the distances that the radio waves are measuring. If the attitude of the airplane varies, the angle of the downwardly directed beam will vary and the indicator on the scale measuring absolute altitude will fluctuate considerably and with pitching of the aircraft the indicator on the scale showin the distance measured by the forwardly directed radio beam will have tremendous fluctuation and be very unreliable as a contourmeter. The lat 2 ter fluctuation and the wrong indication resulting therefrom is more serious. Furthermore when the airplane is pitching and the pilot is maneuvering the ship, as for example in a storm, to keep the airplane on as near level flight as possible, it is not safe to trust the pilot to observe the confusion of the indicators registered on the scales and to depend upon him to react and make the necessary control adjustments of the aircraft to avoid a possible obstruction.

The device described in the above mentionedpatent could only be useful under conditions which seldom exist, that is, when the airplane is maintained on a straight smooth, constant attitude flight. When the airplane is flying over hilly or mountainous regions during periods of poor visibility, the airplane is most apt to be subject to air currents which cause a very bumpy flight.

The principal object of the present invention is to measure the altitude of the airplane and the distance of the ground from a predetermined point ahead of the aircraft by radio waves which emanate from and are received by antennae on the aircraft so mounted that the antennae are positioned in space independent of the attitude of the airplane in flight. The distance ahead of the airplane being measured on the forwardly directed angle of the radio beam is in proportion to the characteristics of the airplane, namely, the cruising speed and the rate of climb.

It is a further object of this invention to provide a means for adjusting the forwardly directed beam angle to take into consideration the normal cruising speed of the airplane and the rate of climb of the particular airplane.

It is a further object of this invention to take the safety of the aircraft out of the hands of the pilot when the ship is flying under automatic control by having the response to the comparison of the forwardly directed beam and the downwardly directed beam override the automatic control and cause the airplane to start'to climb suiiiciently ahead of the obstruction to safely clear it.

Further and other objects will become appar ent from the description of the accompanying drawings which form a part of this disclosure and in which like numerals refer to like parts.

In the drawings:

Figure 1 shows a diagrammatic view of the airplane embodying this invention.

Figure 2 is a fragmentary section through the fuselage showing the antenna.

Figure3 is a section taken on the line 3-3 of FigmeZ.

Figure 4 is a diagrammatic arrangement of the controls.

The airplane shown as l in Figure 1 is shown in flight above the terrain indicated by the line 2. The airplane has mounted in the forward portion of the fuselage an antenna system that sends and receives an ultra shortwave beam vertically downwardly along the-= path' indicarted .as A. also has another .antenna system for sending .andzreceiving a radio beam along the path indicated as L which is set at an angle with respect to the first mentioned beam A. If the. terrain. should suddenly rise as a hill or mountainindicated as M in Figure 1, the dimensionL measured byathe forwardly directed beam would suddenhrishorten; and this shortening would indicate a rise of ground ahead of the airplane. Ifmeans are. not

vious to any one versed in the uses of gyroscopes.

tion of the aircraft. It can readily be seen then that if the airplane is climbing or'pitching the I' radio beam. from antenna 5-wi-ll accurately meas- =.ure,ithe;altitude ofzthe-airplanmand inalike man: ner the radio beam from antenna 6 will accurately #measure the distance to a predetermined point ahead of the airplane on the ground. 7

As shown -i-n -Figure 4, the stabilized antennae 5 and .6 are connected in a system including a radio provided to detect such a rise of ground at a distance sufiiciently ahead of the airplane (toenahle the airplane to gain such :altitude to clear the 0bstruction, the information would-be .valueless.

By this, invention, .the--.disiiance =L-.-is measured from the ..-airplane-,to :apoint ahead-of the airplane on .the ground .hyadjusting the-beam along path L by varying angle .0. Every airplane has a particular cruising-.-speed and is designed for a maximum rate :of climb. If an obstructiomshould loom up ahead-of an .airplane, .aidetecting device must-be such that (the obstruction is vnotedin sufficient time that the..-airplane will-.have time to gain suflicient altitude rats-its. maximum '.rate- 0f climb to .clear-theyobstruction. Therefore the distance ahead of the airplane -.at-.which.the tor-- wardly directedqbeam 1831 011112661 .shouldbefleterminedby the prohable :heig'ht aof the .obstruction that the airplane might encounter in a particular gflight. Whenthe nharacteristics -of-the airplane are {known and the proha-ble -maxima of the variables that will be encountered inthe flight rare determined.-bysimpletrigonomflrythe angle between the sentinel; zbeam measuring altitude and :theyiorwardly ttiireoted ibeam measur n the distance to z zpoiht ahead of the airplane ca easily be determined.

.Since it :is well knownthat an airplane -orer hilly country ,is :SllhiQCtz-tfl \considerablepitohing and rolling, tit zdesirabletoirnonnt the antenna system for this invention in a manner shown-in Figures .2- and, 3. Thetshinof the ifu el i e is forme wi h aperture 4 'threus-hwhich eatendz'antennae 5 and 6, cientenna 5 has aniendgportio 1 for sending and receiving .radio waves vertically downwardly ;to-.;measure ..the=. distance to the ground. Antenna 6 has portion 8 toimeasure the distance by :meanswcf a radio: Vl&V..e,.. i0. anoint ahead of the .airplane.- Antennae 5-and 6 extend from hubs 9 .andsl fl-whichiaresmoun-ted on shafts H supported byYY keHQ-Antennae 5-.and'6rm ay be :adiust d to form :anya esired angle 'cfwone relative :to the .othen-bu-t this angular position after adJustmen-tis iixedand the antennae} :and 6 move about shaft I I in yoke 42: together. -oke I2 :is supported hy fihaifit 1L3. ;-Le,ver {I4 is .mounted to move with. hubs 19 and 110"50 thatemotion of lever .I-A causes theiantenna assemblycf members 5, 6,8 and It tomove as -a1-unit. .1-Linkage 1-5 and she-fi 1:3 are-driven :bya gyro stabilizer housed in box 1-6. Any-conventional gyroscopic stabilizer can be used to thus swing the antenna unit about the axes .43 and .H. For example, a gyroscope as .tmmmi-tteridand receiver 2| which are con- "znpflfifi'editma-nl 1111113. 5 to measure the altitude, and transmitter 22'and receiver 23 are connected to antenna 'fi'to measure the distance indicated as L inil igiire. 1. As can be readily seen from Figure 1, for any angle 0 between the paths A and L, the. distance. I... when the plane is .over level ground,

willlequal the squarerdotof A D? and the ratio 1 of A to L will therefore be equal to the cosine .of-r.

If the terrain is rising ahead, .this ratioof Atoll will be greater thanlcosine 10,. while if the terrain is. falling,..the ratio willbe less .thancosine' 0.. 7 computer .is .so designed that whenever .thisreitio.

is greater thancosine .0, indicating arisein terrain ahead, the computer sendsa signal .into.,control .25

which causes adjustmentsin the automaticpilot 26 to causethe plane toiclimbnntil the ratioLagain falls .to the. predetermined value. received from the antennae iandificanbe said to be combined in the .computerklse that the. climb of the airplane will respondto.meldistanceL exe;

which indicates .aldcwnivard, slope .of the .terraiin.-' WhenL becomesjles's than A divided by cosine .a,

indicating an upward slope cf ;the..terram,-the controls ,areactuated to. cause the airplane to .rise.

The specific details {the receivers, computer V and auto-pilot, control unit form no. part ofIhe presen invention. devices which will pe m the aboyeedescribed functionsQbeing well-known in thelelectromcs art. '..Asan example,however, the V receivingrunits might include a pair .of distance measuring .circuitsof the .type .shown by the-Big gins .et .al. Batent 2,206,896 wherein an ou put voltage isproduced which is directly proportional tothe length-of the path being measured, withthe output-voltages of thetwo units being applied to the computer. .The computer itself might be .any..suitable dividing :netwo-r-k such-as .is,

shown .in the scherbatskoyet a1. Patent 2,129,880, Wherein'the meter 1 29 .is-arranged to directly i-n-.

dicate thera'tio between .-.tw.o .yol-tages applied to;

' the..inpu.t terminals thereof. 0bv-iously asuitable'electric switch ,cou-ld lee-arranged to be auto- I matically closed whenewer, the ratio tas indicated by the positionof the meter pointer.) exceeded the certain predetermined. value (cosine -19) {said switch thereby completing .a :circuit in @an .autopilot .control .unit of. thatype shown y the Borkow Patent 1,869,840 for examplaidcause-the plane to climb until thematic a ain 94115 1120 11 113 desired predetermined fyalue. -...Boykow, fore!!- ample,,this .-could..-.be.dohe bye-connectin the Switch so as .to shuntfroinpoint .43 1110 .52.

other equivalent arrangements. for nroducisng these results; will .be inrtheart.

The signals l/li0i1. 0 any personshilled V If the airplane isbeing flown by the pilot, the control gives an audible or visible signal through member 21. towarn the pilot of the danger ahead.

:From the above description it will be apparent that the operation of this invention for any airplane will be dependent upon the characteristics ofthe airplane. From knowledge of the potentialhazards on the ground along the fiight path, the maximum obstruction can be estimated. The cruising .speed of the airplane and its rate of climb will be known. Therefore, the angle be tween antennae 5 and 6 can be computed and the antennae adjusted; After the airplane has taken off and-its flight altitude attained, it is usual to fly the plane by the automatic pilot. The stabilized antenna described above will continuously measure the altitude and the distance to a point ahead of the airplane and make the necessary adjustments through the computer and control in the automatic pilot to cause the airplane to climb over any'obstruction. The safety of the airplane is assured by the fact that the antenna stabilizing mechanism maintains the measuring equipment in a fixed position in space independent of the attitude of the airplane so that false readings or signals will not be caused 'due to pitching of the airplane in normal flight.

It is to be understood that certain changes, alterations, modifications and substitutions can be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A safety device for an aircraft comprising an antenna support mounted on said aircraft for rotation relative thereto about a first pivot axis parallel to the plane defined by the pitch and roll axes of said aircraft, a pair of directional antennas carried by said support for conjoint rotation relative thereto about a second pivot axis extending substantially perpendicular to said first pivot axis, said antennas being angularly oriented with respect to one another in a plane substantially perpendicular to said second pivot axis whereby a first of said antennas is adapted to transmit and receive radiant energy along a path extending substantially vertically downwardly from said aircraft and said second antenna is adapted to transmit and receive radiant energy along a path extending downwardly and forwardly from said aircraft at a predetermined angle to the vertical, stabilizing means carried by the aircraft for conjointly rotating said antennas about said pivot axes to maintain them in said oriented positions despite pitching or rolling movements of said aircraft, distance measuring means associated with each of said antennas for measuring the distance from said aircraft to the ground along each of said paths, means responsive to said measuring means for comparing said distances, and means responsive to said comparing means for causing said aircraft to climb whenever the ratio of the distance to ground along said vertical path to that along said inclined path exceeds the cosine of the angle between said paths.

2. A safety device for an aircraft comprising an antenna support mounted on said aircraft for rotation relative thereto about a first pivot axis parallel to the plane defined by the pitch and roll axes of said aircraft, a pair of directional antennas carried by said support for conjoint rotation relative thereto about a second pivot axis extending substantially perpendicular to said first pivot axis, said antennas being angularly oriented with respect to one another in a plane substantially perpendicular to said second pivot axis whereby a first of said antennas is adapted to transmit and receive radiant energy along a path extending substantially vertically downwardly from said aircraft and said second antenna is adapted to transmit and receive radiant energy along a path extending downwardly and forwardly from said aircraft at a predetermined angle to the vertical, stabilizing means carried by the aircraft for conjointly rotating said antennas about said pivot axes to maintain them in said oriented positions despite pitching or rolling movements of said aircraft, distance measuring means associated with each of said antennas for measuring the distance from said aircraft to the ground along each of said paths, means responsive to said measuring means for comparing said distances, and means responsive to said comparing means for causing said aircraft to climb whenever the ratio of the distance to ground along said vertical path to that along said inclined path exceeds the cosine of the angle between said paths, said antennas being angularly adjustable relative to one another, whereby the angle between said ipaths may be varied in accordance with the speed of said aircraft and the nature of the terrain 'over which said aircraft is to fly.

3. A safety device for an aircraft comprising a member carried by the aircraft for rotation relative thereto about a pivot axis extending substantially parallel to the roll axis thereof, an antenna support carried by said member for rotation about a second pivot axis perpendicular to said first pivot axis, a pair of directional antennas mounted on said support for rotation therewith, one of said antennas being oriented for transmission along a vertical downward path and the other being oriented for transmission along a path extending downwardly and forwardly at a predetermined angle to the vertical, stabilizing means carried by the aircraft for conjointly rotating said antennas about said pivot axes to maintain said antennas in said oriented positions despite roll and pitching movements of said aircraft, means including said antennas for measuring the distances to the ground along said paths, means responsive to said measuring means for comparing said distances, and means responsive to said comparing means for causing said aircraft to climb whenever the ratio of the distance along said vertical path to that along said inclined path exceeds the cosine of the angle between said paths.

4. A safety device for an aircraft comprising a member carried by the aircraft for rotation relative thereto about a pivot axis extending substantially parallel to the roll axis thereof, an antenna support carried by said member for rotation about a second pivot axis perpendicular to said first pivot axis, a pair of directional antennas mounted on said support for rotation therewith, one of said antennas being oriented for transmission along a vertical downward path and the other being oriented for transmission along a path extending downwardly and forwardly at a predetermined angle to the vertical, stabilizing means carried by the aircraft for conjointly rotating said antennas about said pivot axes to maintain said antennas in said oriented positions despite rolling and pitching movements of said aircraft, means including said antennas for measuring the distances to the ground along said paths, means responsive to said measuring means for comparing said distances, and means responsive:rto sai'd eomparingrameansiforicausing said .zaircraft :to zrelimb "whenever'ithe Tratio iof the distance along said avertical xpath 1130 :*:that :along said-inclinedfpath exceedmtheeosinei ofthe angle between said .-:paths, :said :se'cond. zantenna bein independently angu'larly @adj usta'ble a'relati-ve 1 :to said support whereby the angle between :said paths -:may'.be varied .inaaee'ordanceswiththetspweed of said aircraft-and the mature ot -the intended flight "path. y

. :5. in a SEfBtYZdGViGB for z-an aircraft, distance measuring :means:zcarriedisbyzthe:aircrafit and including :an tantenna support :moun'ted iforcrotation relative thereto zabout perpendicularly re- 1ated' axes,.=-and2a pair of zcgrectional antennas rigidly :carried bysaid support for movement therewith, one i of *said :antennas "being oriented soSas-totransmitandireeeivearadiantvenergysalong a :path :exten'ding substantially wertieally -id0wnwardly 'fromrsaid :aircraft and the :other being oriented so :as -:to transmit :andireceive radiant energy along :an :inclined =path 'extendmgafiownwardly and if orwar'dly'frornthe aircraft at fa predetermined angle "-to' the vertical, said distance measuring meansiinoluding' means for measuring thedistance to groundalong eachwf saidipaths, arcomparatorresponsive"totsaid measuringsmeans for dete'mlining the'raltieof 'sai'dsdistances,rmslns said support about 'said "axes to maintain antennas inssaid'oriented positions despit'e pitch ing orrolling movements of theaircr aft. V

ROGER V REFERENGES CITED "The following references are of 1:reeor ii{in V file "of this patent: p

UNITED STATES'YPATENTSVI j 

